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-   -   Capacitor usage on old mobo (http://www.hardwarecanucks.com/forum/cpus-motherboards/55503-capacitor-usage-old-mobo.html)

Ravenor July 15, 2012 09:06 AM

Capacitor usage on old mobo
 
Ok, so my wife computer finally stopped working and i figured out it was the Asus P5N capacitors that were gone on the mobo. So i had to get it up and running very quickly and replaced the board with a spare Asus P5KPL that i had lying around. Now this board was used in my media box originally but it was not really turned on very much at all.

My question is, How much capacitor usage does a motherboard get when it's plugged in but not turned on?

Perineum July 15, 2012 09:22 AM

The issue isn't how much usage it gets so much as the ones that blew were shitty caps.

The only excuse companies have now for blown caps is the UCC KZG series. United ChemiCon is a reputable company, but the KZG series caps failed prematurely. Use of any other caps is just the company trying to save a buck, and regrettably Asus has done this in the past. I just replaced a handful of caps for a client that was financially unable to replace their motherboard/cpu/ram at this point.

Providing your new motherboard uses solid caps or name brand caps you'll probably retire the board from being too slow long before the caps fail.

Funguseater July 16, 2012 10:41 PM

Hi Ravenor

Yeah, lots of companies are cutting corners on Caps it seems. I have my office full (ok only 3) of LCD monitors that I brought home from the computer recycler, replaced the psu caps and they work great. Most of the damage comes when the capacitors used are not rated for a high enough temperature, they overheat and "leak" or dry out. You can check your other board and see if the Caps are bloated (I would recomend getting a sharpie and making a line across the top of the cap, that way if/when they start to go you'll be ready, you can check on them every 6 months and see if they are about to fail.)

If you are adventerous you can buy some replacement Caps and practice your soldering ;)
Have fun
Fungi

Perineum July 17, 2012 12:20 AM

Well you'll find lots of 105C temp rated caps, but they still fail. Switch mode power supplies are hard on caps and cheap ones tend to let the electrical series resistance creep up. Eventually they fail....

When you replace them with real 105C rated caps from a good manufacturer they tend to last.

KaptCrunch July 17, 2012 08:40 AM

just a note: use ESD soldering iron for the cheap ones have voltage leakage on the tip. or heat up iron then remove plug from wall to solder

first make a list of caps needed, size(mFD),voltage, quanity. usally its all the same mFD rating caps

note what side is the negitive . will see that most MB are marked shaded/filled for the neg side, so not to get the polarity wrong

what I do is break off the bad by bending back and forth then desolder the broken cap wire, this saves heating up the cap to remove it Then use a solder sucker to clear out hole

Perineum July 17, 2012 08:55 AM

... and remember Asus boards have reverse markings for polarity.... :thumb:

MacJunky July 18, 2012 02:00 PM

Quote:

Originally Posted by KaptCrunch (Post 642717)
what I do is break off the bad by bending back and forth then desolder the broken cap wire, this saves heating up the cap to remove it Then use a solder sucker to clear out hole

You risk damaging the pads/vias though. If the cap or a soldered-in battery has leaked the pads/vias can be weakened.
Just desolder it like usual. With braid or a vacuum tool you can quickly get the legs clear enough that they are not attached(or only barely) and the cap drops right out with little fuss.

If you have to work with surface mount caps you can get two soldering irons to very easily heat up both sides at the same time without mechanically stressing the pads.

Stosh August 3, 2012 09:49 AM

if my memory serves me correctly, that asus board came out right around the time of a big counterfeit capacitor scandal.

apparently some company stole the secret production methods for capacitors, only they didn't quite get it right.

they wound up on a large number of boards, and wound up with huge failure rates.

Perineum August 3, 2012 10:22 AM

google "capacitor plague"


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